10,418. Brown, C. R. B. May 4. Siphons.-Apparatus for discharging sewage or other liquid from a tank to a series of filter-beds or other receptacles in sequence consists of domed siphons, each of which is connected by a pipe 4 to an apparatus of the construction shown in Fig. 2. At each filling of the tank, air is forced from the siphons through the pipes 4 to chambers 9 communicating by pipes 10 with chambers 5. The chambers 5, 9 of each apparatus contain a liquid such as a non-drying oil or mercury, and the air pressure forces the liquid from the chamber 5 up a pipe 6 to an open vessel 7. On discharge of the tank, the air pressure is released and liquid in the tank 7 above the inlet of the pipe 6 is returned to the chamber 5, while that below the inlet passes by the pipe 8 to the chamber 9. The division of the liquid between the chambers 5, 9 is initially different for each apparatus, and discharge of the tank after any filling takes place through that siphon, for which the corresponding chamber 5 is completely emptied by the filling, the air being released from the dome of this siphon through the pipe 4, chamber 5, and pipe 6. The tank 5 is re-filled from the tank 9 by means of the siphon 11. In a modification, the chambers 5, 9 are placed side by side, the pipe 10 does not enter the chamber 5, but connects the chamber 9 to the pipe 6, and a bent tube, through which the oil is drawn by the suction due to the discharge of the main siphon, replaces the siphon 11. The bent tube may be fitted with a cock governed by a ball in the main tank or in a separate cistern. Fig. 4 shows an arrangement for stopping the action of a discharging- siphon. The chamber 15 contains oil and a mercury seal covering the end of a pipe 19 communicating with the atmosphere or a compressed air-vessel. The suction of the discharge through the siphon draws the oil to the chamber 16 through the valved pipe 17, breaks the seal of the pipe 19, and admits air which stops the discharge. The oil is then returned to the chamber 15. Fig. 5 shows apparatus for controlling the period during which a filter bed 20 is kept full of liquid. Air from the siphon forces oil from a chamber 21 up a pipe 22 and through a tap 24, until the seal is broken and air admitted. The oil is returned from the vessel 23 to the chamber 21 through a pipe 25 sealed by mercury at its lower end. In modified apparatus a U-tube replaces the sealed tube 25. According to the Provisional Specification, sand or other suitable granular material may be used instead of the non-drying liquid, and the ball cock, mentioned in connexion with the modified form of the apparatus shown in Fig. 2, may be replaced by a needle-valve suspended from a float acting in the short leg of a siphon in the vessel 9, the long leg of the siphon communicating with the vessel 5. In addition to the needle-valve, a flap valve may be employed mounted on one arm of a lever, the other arm of which carries an oil tray.